With development of mobile communication technology, the need for positioning service is gradually increased. Applicable scenarios of the positioning service present a tendency of diversity, such as emergency help positioning, crime tracking and positioning, navigation and traffic control, and so on. However, no matter how diversified the applicable scenarios are, it is always desired to achieve a reliable, efficient and fast positioning to meet demands for positioning in the industry.
Currently, there are many kinds of positioning methods in the mobile communication technology, and in these methods, enhanced cell identification (CID, Cell Identification) positioning, downlink positioning (observed time difference of arrival OTDOA, method of Observed Time Difference of Arrival) or the like is the most common positioning technology.
The CID positioning is a method to represent a geographic position of a mobile station by the ID of a cell in which the mobile station is located. In the mobile positioning, the CID positioning is a positioning method which is most convenient, simplest and easiest to realize, however, the positioning accuracy thereof is low because the positioning accuracy depends on the magnitude of radius of cell, and if the radius of cell is large, the position of the cell to which the mobile station belongs can not accurately reflect the geographic position of the mobile station, resulting in a serious positioning error.
The principle of the OTDOA positioning is as follows: when there are three or more base stations in the system, the position of a terminal can be determined by the time difference of arrival (TDOA: Time Difference of Arrival) of downlink communication signals from the different base stations. That is, an enhanced serving mobile location center (e-SMLC, Enhanced Serving Mobile Location Center) at the network side collects the PRS sending configurations of the base stations and sends the same to the mobile station as assistance data. The base stations send the PRS on downlink, and the mobile station receives the PRS from a plurality of the positioning base stations and recognizes position of the first accessible path of each PRS, so as to obtain the TDOA of the PRS among the different base stations and report the same to the e-SMLC; the e-SMLC receives TDOA of the PRS from the different base stations through the mobile station, which can be mapped into the distance difference between the mobile station and the different base stations. Then, the accurate position of the mobile station can be obtained by e-SMLC through mathematical calculation. However, the accuracy of the OTDOA positioning largely depends on the receipt of the PRS signal and the estimation of the first accessible path. Although the positioning of a terminal can be achieved in some dense urban or some indoor scenarios, since it is required to estimate the TDOA of the signals, the wireless propagation environment of the dense urban and indoor scenarios would affect the multipath of the signals, resulting in that the TDOA can not exactly reflect the linear distance difference from two base stations to the UE, thus the positioning error is increased.
In the process of researching and practicing the prior art, the inventor of the present disclosure found that in the existing implementations, neither the CID positioning nor the OTDOA positioning can effectively improve the positioning accuracy, thus the problem to be solved currently is how to effectively improve the positioning accuracy.